The present invention relates to a polymerizable composition comprising a) at least one ethylenically unsaturated monomer and b) a nitroxide initiator compound. Further aspects of the present invention are a process for polymerizing ethylenically unsaturated monomers, novel initiator compounds and their use for polymerization, and also the polymer or copolymer produced by this process.
More specifically, in one of its aspects the present invention relates to polymerizable compositions and polymerization processes which provide polymeric resin products having low polydispersity , which polymerization processes proceed with enhanced monomer to polymer conversion efficiencies. In particular, this invention relates to stable free radical-mediated polymerization processes which provide homopolymers, random copolymers, block copolymers, multiblock copolymers, graft copolymers and the like, at enhanced rates of polymerization and enhanced monomer to polymer conversions.
Polymers or copolymers prepared by free radical polymerization processes inherently have broad molecular weight distributions or polydispersities which are generally higher than about four. One reason for this is that most of the free radical initiators have half lives that are relatively long, ranging from several minutes to many hours, and thus the polymeric chains are not all initiated at the same time and the initiators provide growing chains of various lengths at any time during the polymerization process. Another reason is that the propagating chains in a free radical process can react with each other in processes known as combination and disproportionation, both of which are irreversibly chain-terminating reaction processes. In doing so, chains of varying lengths are terminated at different times during the reaction process, resulting in resins consisting of polymeric chains which vary widely in length from very small to very large and which thus have broad polydispersities. If a free radical polymerization process is to be used for producing narrow molecular weight distributions, then all polymer chains must be initiated at about the same time and termination of the growing polymer-chains by combination or disproportionation processes must be avoided.
Conventional radical polymerization reaction processes pose various significant problems, such as difficulties in predicting or controlling the molecular weight, the polydispersity and the modality of the polymers produced. These prior art polymerization processes produce polymers having broad polydispersities and in some instances, low polymerization rates. Furthermore, free radical polymerization processes in bulk of the prior art are difficult to control because the polymerization reaction is strongly exothermic and an efficient heat removal in the highly viscous polymer is mostly impossible. The exothermic nature of the prior art free radical polymerization processes often severely restricts the concentration of reactants or the reactor size upon scale-up.
Due to the above mentioned uncontrollable polymerization reactions, gel formation in conventional free radical polymerization processes are also possible and cause broad molecular weight distributions and/or difficulties during filtering, drying and manipulating the product resin.
U.S. Pat. No. 4 581 429 to Solomon et al., issued Apr. 8, 1986, discloses a free radical polymerization process which controls the growth of polymer chains to produce short chain or oligomeric homopolymers and copolymers, including block and graft copolymers. The process employs an initiator having the formula (in part) Rxe2x80x2Rxe2x80x3Nxe2x80x94Oxe2x80x94X, where X is a free radical species capable of polymerizing unsaturated monomers. The reactions typically have low conversion rates. Specifically mentioned radical Rxe2x80x2Rxe2x80x3Nxe2x80x94Oxe2x80xa2 groups are derived from 1,1,3,3 tetraethylisoindoline, 1,1,3,3 tetrapropylisoindoline, 2,2,6,6 tetramethylpiperidine, 2,2,5,5 tetramethylpyrrolidine or di-t-butylamine.
EP-A-735 052 discloses a method of preparing thermoplastic polymers of narrow polydispersities by free radical-initated polymerization, which comprises adding a free radical initiator and a stable free radical agent to the monomer compound.
This method has the disadvantage that uncontrollable recombinations of initiator radicals occur immidiately after their formation, thus producing variable ratios between initiator radicals and stable free radicals. Consequently there is not enough control about the polymerization process.
There is therefore still a need for polymerization processes for the preparation of narrow polydispersity polymeric resins with defined molecular weights using the economical free radical polymerization techniques. These polymerization processes will also control the physical properties of the polymers such as viscosity, hardness, gel content, processability, clarity, high gloss, durability, and the like.
The polymerization processes and resin products of the present invention are useful in many applications, including a variety of specialty applications, such as for the preparation of block copolymers which are useful as compatibilizing agents for polymer blends, or dispersing agents for coating systems or for the preparation of narrow molecular weight resins or oligomers for use in coating technologies and thermoplastic films or as toner resins and liquid immersion development ink resins or ink additives used for electrophotographic imaging processes.
Surprisingly, it has now been found that it is possible to overcome the afore mentioned shortcomings of the prior art by providing a polymerizable composition containing specific initiator compounds. The majority of these compounds are novel and they are also an object of the present invention. Polymerization of the composition results in a polymer or copolymer of narrow polydispersity and a high monomer to polymer conversion even at relatively low temperatures and at short reaction times, making the polymerization process particularly suitable for industrial applications. The resulting copolymers are of high purity and in many cases colourless, therefore not requiring any further purification.
One object of the present invention is to provide a polymerizable composition, comprising
a) at least one ethylenically unsaturated monomer or oligomer, and
b) an initiator compound of formula (I) 
wherein n is 0 or 1
R1, R2, R3 are each independently of one another hydrogen, halogen, NO2, cyano, xe2x80x94CONR5R6, xe2x80x94(R9)COOR4, xe2x80x94C(O)xe2x80x94R7, xe2x80x94OR8, xe2x80x94SR8, xe2x80x94NHR8, xe2x80x94N(R8)2, carbamoyl, di(C1-C18alkyl)carbamoyl, xe2x80x94C(xe2x95x90NR5)(NHR6);
unsubstituted C1-C18alkyl, C2-C18alkenyl, C2-C18alkynyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or C1-C18alkyl, C2-C18alkenyl, C2-C18 alkynyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or
phenyl, naphthyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or R2 and R3, together with the linking carbon atom, form a C3-C12 cycloalkyl radical, a (C4-C12 cycloalkanon)-yl radical or a C3-C12cycloalkyl radical containing at least one O atom and/or a NR8 group; or if n is 1
R4 is hydrogen, C1-C18alkyl, phenyl, an alkali metal cation or a tetraalkylammonium cation; R5 and R6 are hydrogen, C1-C18alkyl, C2-C18alkyl which is substituted by at least one hydroxy group or, taken together, form a C2-C12alkylene bridge or a C2-C12-alkylene bridge interrupted by at least one O or/and NR8 atom;
R7 is hydrogen, C1-C18alkyl or phenyl;
R8 is hydrogen, C1-C18alkyl or C2-C18alkyl which is substituted by at least one hydroxy group;
R9 is C4-C12alkylen or a direct bond;
R10 is C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom, C9-C11phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom, C9-C11phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or
phenyl, naphthyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino; if n is 1
R11 is C1-C18alkyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or
C1-C18alkyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or halogen, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or a polycyclic cycloaliphatic ring system or a polycyclic cycloaliphatic ring system with at least one di- or trivalent nitrogen atom; or
R10 and R11 together form a C2-C12alkylene bridge, a C3-C12alkylen-on bridge or a C2-C12alkylene bridge which is interrupted by at least one O or N atom, which bridges are unsubstituted or substituted with C1-C18alkyl, hydroxy(C1-C4)alkyl, phenyl, C7-C9phenylalkyl, NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino,
R12 is hydrogen, xe2x80x94(R9)COOR4, cyano, xe2x80x94OR8, xe2x80x94SR8, xe2x80x94NHR8, xe2x80x94N(R8)2, xe2x80x94NHxe2x80x94C(O)xe2x80x94R8, C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or C1-C18alkyl, C2-C18alkenyl, C2-C18 alkynyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or
phenyl, naphthyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino, di(C1-C4alkyl)amino; or R11 and R12 together with the linking carbon atom form a C3-C12cycloalkyl radical; with the proviso that bis-(2-cyano-2-propyl)-N-phenylhydroxylamine is excluded and if n=0 R10 is different from the group xe2x80x94CR1R2R3.
The initiator compound of formula (I) is preferably present in an amount of 0.01 mol-% to 30 mol-%, more preferably in an amount of 0.1 mol-% to 10 mol-% and most preferably in an amount of 0.1 to 5 mol-%, based on the monomer, oligomer or monomer/oligomer mixture used.
Preferrably compounds of formula (I) do not contain the structural element 2,2,6,6 tetra(C1-C4alkyl)piperidine, 2,2,5,5 tetra(C1-C4alkyl)pyrrolidin or 1,1,3,3 tetra(C1-C4alkyl)isoindoline
Halogen is fluoro, chloro, bromo or iodo.
The alkyl radicals in the various substituents may be linear or branched. Examples of alkyl containing 1 to 18 carbon atoms are methyl, ethyl, propyl, isopropyl, butyl, 2-butyl, isobutyl, t-butyl, pentyl, 2-pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, t-octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl and octadecyl.
The alkenyl radicals in the various substituents may be linear or branched. Examples of C2-C18alkenyl are vinyl, allyl, 2-methylallyl, butenyl, hexenyl, undecenyl and octadecenyl. Preferred alkenyls are those, wherein the carbon atom in the 1-position is saturated and where the double bond is not activated by substituents like O, Cxe2x95x90O, and the like. Examples of C2-C18alkynyl are ethynyl, 2-butynyl, 3-hexynyl, 5-undecynyl, 6-octadecynyl. The alkynyl radicals may be linear or branched.
C7-C9phenylalkyl is for example benzyl, phenylpropyl, xcex1,xcex1-dimethylbenzyl or xcex1-methylbenzyl.
C9-C11phenylalkyl is for example xcex1,xcex1-dimethylbenzyl, xcex1,xcex1-metylethylbenzyl or xcex1,xcex1-diethylbenzyl.
C3-C12cycloalkyl which is unsubstituted or substituted by 1, 2 or 3 C1-C4alkyl is typically cyclopropyl, cyclopentyl, methylcyclopentyl, dimethylcyclopentyl, cyclohexyl, methylcyclohexyl.
Alkyl substituted by xe2x80x94OH is typically 2-hydroxyethyl, 2-hydroxypropyl or 2-hydroxybutyl.
C1-C18Alkyl substituted by C1-C18alkoxy, preferably by C1-C4alkoxy, in particular by methoxy or ethoxy, is typically 2-methoxyethyl, 2-ethoxyethyl, 3-methoxypropyl, 3-ethoxypropyl, 3-butoxypropyl, 3-octoxypropyl and 4-methoxybutyl.
C1-C18Alkyl substituted by di(C1-C4alkyl)amino is preferably e.g. dimethylamino, diethylamino, 2-dimethylaminoethyl, 2-diethylaminoethyl, 3-dimethylaminopropyl, 3-diethylaminopropyl, 3-dibutylaminopropyl and 4-diethylaminobutyl.
C1-C18AIkyl substituted by C1-C4alkylamino is preferably e.g. methylamino, ethylamino, 2-methylaminoethyl, 2-ethylaminoethyl, 3-methylaminopropyl, 3-ethylaminopropyl, 3-butylaminopropyl and 4-ethylaminobutyl.
C1-C8AIkoxy and, preferably C1-C4alkoxy, are typically methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, pentoxy, isopentoxy, hexoxy, heptoxy or octoxy.
C1-C4Alkylthio is typically thiomethyl, thioethyl, thiopropyl, thioisopropyl, thiobutyl and thioisobutyl.
C3-C12cycloalkyl interrupted by at least on nitrogen or oxygen atom is typically oxiran, 1,4-dioxane, tetrahydrofuran, xcex3-butyrolactone, xcex5-caprolactam, oxirane, aziridine, diaziridine, pyrrole, pyrrolidine, thiophen, furan, pyrazole, imidazole, oxazole, oxazolidine, thiazole, pyran, thiopyran, piperidine or morpholine.
Examples of C2-C12alkylene bridges, preferably of C2-C6alkylene bridges, are ethylene, propylene, butylene, pentylene, hexylene.
C2-C12alkylene bridges interrupted by at least one N or O atom are, for example, xe2x80x94CH2xe2x80x94Oxe2x80x94CH2xe2x80x94CH2, xe2x80x94CH2xe2x80x94Oxe2x80x94CH2xe2x80x94CH2, xe2x80x94CH2xe2x80x94Oxe2x80x94CH2xe2x80x94CH2xe2x80x94CH2xe2x80x94CH2xe2x80x94, xe2x80x94CH2xe2x80x94Oxe2x80x94CH2xe2x80x94CH2xe2x80x94Oxe2x80x94CH2xe2x80x94, xe2x80x94CH2xe2x80x94NHxe2x80x94CH2xe2x80x94CH2, xe2x80x94CH2xe2x80x94NHxe2x80x94CH2xe2x80x94CH2xe2x80x94CH2, xe2x80x94CH2xe2x80x94NHxe2x80x94CH2xe2x80x94CH2xe2x80x94CH2xe2x80x94CH2xe2x80x94, xe2x80x94CH2xe2x80x94NHxe2x80x94CH2xe2x80x94CH2xe2x80x94NHxe2x80x94CH2xe2x80x94 or xe2x80x94CH2xe2x80x94NHxe2x80x94CH2xe2x80x94CH2xe2x80x94Oxe2x80x94CH2xe2x80x94.
Examples for C4-C12cycloalkanone-yl are cyclopentanone-yl, cyclohexanone-yl or cycloheptanone-yl.
Phenyl substituted by 1, 2 or 3 C1-C4alkyl or C1-C4alkoxy is typically methylphenyl, dimethylphenyl, trimethylphenyl, t-butylphenyl, di-t-butylphenyl, 3,5-di-t-butyl-4-methylphenyl, methoxyphenyl, ethoxyphenyl and butoxyphenyl.
Examples of polycyclic cycloaliphatic ring systems are adamantane, cubane, twistane, norbornane, bycyclo[2.2.2]octane or bycyclo[3.2.1]octane.
An example of a polycyclic heterocycloaliphatic ring system is hexamethylentetramine (urotropine).
The C-atom to which the substituents R1, R2 and R3 are bound is preferably a secondary or tertiary C-atom more preferably it is a tertiary C-atom.
Examples for C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom are the following groups: 
The monomers suitable for use in the present invention may be water-soluble or water-insoluble. Water soluble monomers contain typically a carboxylic acid group or a salt of a carboxylic acid group. Water insoluble monomers are typically free of acid and phenolic groups.
Typical monoethylenically unsaturated monomers free of carboxylic acid which are suitable for this invention include the alkyl esters of acrylic or methacrylic acids such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and isobutyl methacrylate; the hydroxyalkyl esters of acrylic or methacrylic acids, such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; acrylamide, methacrylamide, N-tertiary butylacrylamide, N-methylacrylamide, N,N-dimethylacrylamide; acrylonitrile, methacrylonitrile, allyl alcohol, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, phosphoethyl methacrylate, N-vinylpyrrolidone, N-vinylformamide, N-vinylimidazole, vinyl acetate, conjugated dienes such as butadiene or isoprene, styrene, styrenesulfonic acid salts, vinylsulfonic or 2-acrylamido-2-methylpropane-sulfonic acid salts and acryloyl chloride.
The polymerizable composition of the present invention may additionally comprise a solvent selected from the group consisting of water, alcohols, esters, ethers, ketones, amides, sulfoxides, hydrocarbons and halogenated hydrocarbons.
Preferred ethylenically unsaturated monomers or oligomers are selected from the group consisting of styrene, substituted styrene, conjugated dienes, acrolein, vinyl acetate, (alkyl)acrylic acidanhydrides, (alkyl)acrylic acid salts, (alkyl)acrylic esters or (alkyl)acrylamides.
Particularly preferred ethylenically unsaturated monomers are styrene, xcex1 methyl styrene, xcfx81-methyl styrene or a compound of formula CH2xe2x95x90C(Ra)xe2x80x94(Cxe2x95x90Z)xe2x80x94Rb, wherein Ra is hydrogen or C1-C4alkyl, Rb is NH2, O(Me), glycidyl, unsubstituted C1-C18alkoxy or hydroxy-substituted C1-C18alkoxy, unsubstituted C1-C18alkylamino, di(C1-C18alkyl)amino, hydroxy-substituted C1-C18alkylamino or hydroxy-substituted di(C1-C18alkyl)amino;
Me is a monvalent metal atom and
Z is oxygen or sulfur.
Typical metal atoms are Na, K or Li.
Examples and preferences for alkyl, alkoxy, alkylamino, dialkylamino and hydroxy-substituted alkoxy are afore mentioned.
In a particular preferred composition Ra is hydrogen or methyl, Rb is NH2, glycidyl, unsubstituted or with hydroxy substituted C1-C4alkoxy, unsubstituted C1-C4alkylamino, di(C1-C4alkyl)amino, hydroxy-substituted C1-C4alkylamino or hydroxy-substituted di(C1-C4alkyl)amino;and
Z is oxygen.
Most preferred is a polymerizable composition, wherein the ethylenically unsaturated monomer is methylacrylate, ethylacrylate, butylacrylate, isobutylacrylate, tert. butylacrylate, hydroxyethylacrylate, hydroxypropylacrylate, dimethylaminoethylacrylate, glycidylacrylates, methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, dimethylaminoethyl(meth)acrylate, glycidyl(meth)acrylates, acrylonitrile, acrylamide or methacrylamide.
Examples of comonomers suitable for use in the present invention are C3-C6ethylenically unsaturated monocarboxylic acids as well as the alkali metal salts and ammonium salts thereof. The C3-C6ethylenically unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, crotonic acid, vinylacetic acid and acryloxypropionic acid. Acrylic acid and methacrylic acid are the preferred monoethylenically unsaturated monocarboxylic acid monomers.
Examples for C8-C16 ethylenically unsaturated phenolics, which may also be used as comonomers include 4-hydroxy styrene, 4-hydroxy, xcex1-methyl styrene, and 2,6-ditert. butyl, 4-vinyl phenol.
Another class of carboxylic acid monomers suitable for use as comonomers in this invention are C4-C6-ethylenically unsaturated dicarboxylic acids and the alkali metal and ammonium salts thereof as well as the anhydrides of the cis-dicarboxylic acids. Suitable examples include maleic acid, maleic anhydride, itaconic acid, mesaconic acid, fumaric acid and citraconic acid. Maleic anhydride and itaconic acid are the preferred monoethylenically unsaturated dicarboxylic acid monomer(s).
The acid monomers suitable for use in this invention may be in their acid forms or in the form of the alkali metal salts or ammonium salts of the acid. Suitable bases useful for neutralizing the monomer acids include sodium hydroxide, ammonium hydroxide, potassium hydroxide, and the like. The acid monomers may be neutralized to a level of from 0 to 50% and, preferably, from 0 to about 20%. In many cases, the carboxylic acid monomers may be used in the completely neutralized form. The monomers may be neutralized prior to or during polymerization.
Preferred are neutralized carboxylic acid monomers or anhydrides.
Preferred initiator compounds are those, wherein n is 0 or 1;
R1, R2, R3 are each independently of one another NO2, cyano, xe2x80x94(R9)COOR4, xe2x80x94CONR5R6, xe2x80x94C(O)xe2x80x94R7, xe2x80x94OR8, carbamoyl, di(C1-C18alkyl)carbamoyl, xe2x80x94C(xe2x95x90NR5)(NHR6); unsubstituted C1-C18alkyl, C7-C9phenylalkyl or C3-C12cycloalkyl; or C1-C18alkyl, C7-C9phenylalkyl or C3-C12cycloalkyl, which are substituted by amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or phenyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or R2 and R3, together with the linking carbon atom, form a C3-C12 cycloalkyl radical; R4 is, C1-C18alkyl, phenyl, an alkali metal cation or a tetraalkylammonium cation; R5 and R6 are hydrogen, C1-C18alkyl, C2-C18alkyl which is substituted by at least one hydroxy group or, taken together, form a C2-C12alkylene bridge;
R7 is hydrogen, C1-C18alkyl or phenyl;
R8 is C1-C18alkyl or C2-C18alkyl which is substituted by at least one hydroxy group; and R9 is C1-C4alkylen or a direct bond.
R10 is C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom, phenyl, C9-C11phenylalkyl or C3-C12cycloalkyl;
if n is 1
R11 is C1-C18alkyl, C7-C9phenylalkyl or C3-C12cycloalkyl or R10 and R11 together form a C2-C12alkylene bridge or a C2-C12alkylene bridge which is interrupted by at least one O or N atom, which bridges are unsubstituted or substituted with C1C18alkyl;
R12 is, unsubstituted C1-C18alkyl, phenyl, C7-C9phenylalkyl or C3-C12cycloalkyl or R11 and R12 together with the linking carbon atom, form a C3-C12 cycloalkyl radical.
More preferred are initiators, wherein n is 0 or 1;
R1, R2, R3 are each independently of one another NO2, cyano, xe2x80x94(R9)COOR4, xe2x80x94CONR5R6, xe2x80x94C(O)xe2x80x94R7, xe2x80x94OR8, carbamoyl, di(C1-C8alkyl)carbamoyl, xe2x80x94C(xe2x95x90NR5)(NHR6); unsubstituted C1-C12alkyl, C7-C9phenylalkyl or C5-C7cycloalkyl; or C1-C8alkyl, C7-C9phenylalkyl or C5-C7cycloalkyl or, which are substituted by amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or phenyl,
or R2 and R3, together with the linking carbon atom, form a C5-C7cycloalkyl radical;
R4 is C1-C8alkyl, phenyl, an alkali metal cation or a tetraalkylammonium cation;
R5 and R6 are hydrogen, C1-C8alkyl, C2-C8alkyl which is substituted by at least one hydroxy group or, taken together, form a C2-C6alkylene bridge;
R7 is hydrogen, C1-C8alkyl or phenyl;
R8 is C1-C8alkyl or C2-C8alkyl which is substituted by at least one hydroxy group;
R9 is C1-C4alkylen or a direct bond;
R10 is C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom or phenyl;
if n is 1
R11 is C1-C18alkyl, phenyl or C7-C9phenylalkyl or
R10 and R11 together form a C2-C12alkylene bridge or a C2-C12alkylene bridge which is interrupted by at least one O or N atom, which bridges are unsubstituted or substituted with C1-C18alkyl;
R12 is unsubstituted C1-C18alkyl or phenyl.
Particularly preferred initiators are those, wherein n is 0 or 1;
R1, R2, R3 are each independently of one another NO2, cyano, xe2x80x94C(O)xe2x80x94R7, xe2x80x94OR8, unsubstituted C1-C12alkyl or phenyl, which is unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino;
or R2 and R3, together with the linking carbon atom, form a C5-C7 cycloalkyl radical;
R8 is C1-C8alkyl or C2-C8alkyl which is substituted by at least one hydroxy group and R10 is C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom, phenyl or C9-C11phenylalkyl;
if n is 1
R11 is C1-C12alkyl; or
R10 and R11 together form a C2-C6alkylene bridge which is unsubstituted or substituted with C1-C4alkyl;
R12 is hydrogen, unsubstituted C1-C4alkyl or phenyl.
Preferably n is 0; R1 is cyano; R2 and R3 are each independently of one another unsubstituted C1-C12alkyl or phenyl; or R2 and R3, together with the linking carbon atom, form a C5-C7cycloalkyl radical; R10 is C4-C12alkyl bound via a tertiary C-atom to the nitrogen atom, C9-C11phenylalkyl or phenyl.
Another preferred group is wherein n is 1 R1 is cyano; R2 and R3 are each independently of one another unsubstituted C1-C12alkyl or phenyl;
or R2 and R3, together with the linking carbon atom, form a C5-C7 cycloalkyl radical;
R10 is C4-C12alkyl bound via a tertiary C-atom to the nitrogen atom, C9-C11phenylalkyl or phenyl; or
R10 and R11 together form a C2-C6alkylene bridge which is unsubstituted or substituted with C1-C4alkyl; and
R12 is C1-C4alkyl.
This invention also relates to a free radical polymerization process and polymers obtained thereby, which process overcomes many of the problems and disadvantages of the afore mentioned prior art processes.
This process is used for preparing an oligomer, a cooligomer, a polymer or a copolymer -block or random- by free radical polymerization of at least one ethylenically unsaturated monomer or oligomer, which comprises (co)polymerizing the monomer or monomers/oligomers in the presence of an initiator compound of formula (I) 
(I), under reaction conditions capable of effecting scission of the Oxe2x80x94C bond to form two free radicals, the radical xe2x80xa2CR1R2R3 being capable of initiating polymerization.
Preferably, the scission of the Oxe2x80x94C bond is effected by heating, ultrasonic treatment or exposure to actinic radiation.
To perform the scission of the Oxe2x80x94C bond by heating, the temperature is particularly preferably raised to more than 50xc2x0 C. and less than 160xc2x0 C.
The process may be carried out in the presence of an organic solvent or in the presence of water or in mixtures of organic solvents and water. Additional cosolvents or surfactants, such as glycols or ammonium salts of fatty acids, may be present. Other suitable cosolvents are described hereinafter.
Preferred processes use as little solvents as possible. In the reaction mixture it is preferred to use more than 30% by weight of monomer and initiator, particularly preferably more than 50% and most preferrably more than 80%.
If organic solvents are used, suitable solvents or mixtures of solvents are typically pure alkanes (hexane, heptane, octane, isooctane), hydrocarbons (benzene, toluene, xylene), halogenated hydrocarbons (chlorobenzene), alkanols (methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether), esters (ethyl acetate, propyl, butyl or hexyl acetate) and ethers (diethyl ether, dibutyl ether, ethylene glycol dimethyl ether), or mixtures thereof.
The aqueous polymerization reactions can be supplemented with a water-miscible or hydrophilic cosolvent to help ensure that the reaction mixture remains a homogeneous single phase throughout the monomer conversion. Any water-soluble or water-miscible cosolvent may be used, as long as the aqueous solvent medium is effective in providing a solvent system which prevents precipitation or phase separation of the reactants or polymer products until after all polymerization reactions have been completed. Exemplary cosolvents useful in the present invention may be selected from the group consisting of aliphatic alcohols, glycols, ethers, glycol ethers, pyrrolidines, N-alkyl pyrrolidinones, N-alkyl pyrrolidones, polyethylene glycols, polypropylene glycols, amides, carboxylic acids and salts thereof, esters, organosulfides, sulfoxides, sulfones, alcohol derivatives, hydroxyether derivatives such as butyl carbitol or cellosolve, amino alcohols, ketones, and the like, as well as derivatives thereof and mixtures thereof. Specific examples include methanol, ethanol, propanol, dioxane, ethylene glycol, propylene glycol, diethylene glycol, glycerol, dipropylene glycol, tetrahydrofuran, and other water-soluble or water-miscible materials, and mixtures thereof. When mixtures of water and water-soluble or water-miscible organic liquids are selected as the aqueous reaction media, the water to cosolvent weight ratio is typically in the range of about 100:0 to about 10:90.
The initiator compound is preferably present in an amount of 0.01 mol-% to 30 mol-%, more preferably in an amount of 0.1 mol-% to 10 mol-% and most preferably in an amount of 0.1 mol-% to 5 mol-%, based on the monomer or monomer mixture used.
When monomer mixtures or monomer/oligomer mixtures are used, the calculation of mol-% is based on an average molecular weight of the mixture.
Hydrophilic monomers, polymers and copolymers of the present invention can be separated from one another or from the polymerization reaction mixture by, for example, changing the pH of the reaction media and by other well known conventional separation techniques.
The polymerization temperature may range from about 50xc2x0 C. to about 180xc2x0 C., preferably from about 80xc2x0 C. to about 150xc2x0 C. At temperatures above about 180xc2x0 C., the controlled conversion of the monomer into polymer decreases, and uncertain and undesirable by-products like thermally initiated polymer are formed or destruction of the polymerization regulator may occur. Frequently, these by-products discolor the polymer mixture and a purification step may be required to remove them, or they may be intractable.
Therefore the surprisingly high reactivity of the present initiators which are already active at relatively low temperatures leads to short reaction times. The resulting polymers are usually colourless and they can be used in most cases without any further purification step. This is an important advantage when industrial scale-up is considered.
After the polymerizing step is complete, the formed (co)polymer obtained is isolated. The isolating step of the present process is conducted by known procedures, e.g. by distilling off the unreacted monomer or by precipitation in a suitable nonsolvent, filtering the precipitated polymer followed by washing and drying the polymer.
Yet another embodiment of this invention is a process for preparing a block copolymer involving at least two stages, which comprises forming a polymer with alkoxyamine end groups of the general structure of formula II 
wherein n, R1, R2, R3, R10 R11 and R12 are as defined above, the polymer containing the initiator group xe2x80x94CR1R2R3 and having the oxyamine group essentially attached as terminal group, and adding a further monomer followed by heating to form a block copolymer.
The homopolymers or copolymers may also be prepared in a so called in xe2x80x9csitu processxe2x80x9d, which means that the compounds of formula (I) are prepared from a radical xe2x80xa2CR1R2R3 and a compound of formula R10NO or 
in the presence of an ethylenically unsaturated monomer or oligomer. The radical xe2x80xa2CR1R2R3 itself may be prepared as described below, preferably from a compound which liberates the radical upon heating. Under such conditions formation of the compounds of formula (I), their scission and polymerization occur simultaneously. By changing the reaction temperature different pathways of the reaction are favored. It is important to note, that under such reaction conditions still high conversion rates in short reaction times and low polydispersities are achieved.
It is also possible to add the ethylenically unsaturated monomer or oligomer subsequently to the mixture of a radical initiator and a compound of formula R10NO or 
In this case a compound of formula (I) is prepared to a certain amount, which may be up to 100% and subsequently the monomer is added without further isolating the compound of formula (I).
Therefore another object of the invention is a process for preparing an oligomer, a cooligomer, a polymer or a copolymer (block or random) by free radical polymerization of at least one ethylenically unsaturated monomer or oligomer, which comprises generating a free radical xe2x80xa2CR1R2R3 (V) from a compound capable of eliminating a neutral molecule, or undergoing Cxe2x80x94C bond-scission upon thermal or photochemical treatment, or by hydrogen abstraction from a compound R1R2R3Cxe2x80x94H in reaction with reactive radicals, and reacting the free radical xe2x80xa2CR1R2R3 (V) with a compound R10NO or 
in a solvent which does not interfere with the radical reaction in the presence of at least one ethylenically unsaturated monomer or oligomer.
Suitable monomers are those mentioned above. The polymer of formula (II) may be isolated prior to the next reaction step or it may be used without isolation, and the second monomer is added to the reaction mixture of the first step.
Block copolymers are, for example, block copolymers of polystyrene and polyacrylate (e.g., Poly(styrene-co-acrylate) or Poly(styrene-co-acrylate-co-styrene). They are usefull as adhesives or as compatibilizers for polymer blends or as polymer toughening agents. Poly(methylmethacrylate-co-acrylate) diblock copolymers or Poly(methylacrylate-co-acrylate-co-methacrylate) triblock copolymers) are useful as dispersing agents for coating systems, as coating additives (e.g. rheological agents, compatibilizers, reactive diluents) or as resin component in coatings(e.g. high solid paints) Block copolymers of styrene, (meth)acrylates and/or acrylonitrile are useful plastics, elastomers and adhesives.
Furthermore, block copolymers of this invention, wherein the blocks alternate between polar monomers and non-polar monomers, are useful in many applications as amphiphilic surfactants or dispersants for preparing highly uniform polymer blends.
The (co)polymers of the present invention may have a number average molecular weight from 1000 to 400000 g/mol, preferably from 2000 to 250000 g/mol and, more preferably, from 2000 to 200000 g/mol. When produced in bulk, the number average molecular weight may be up to 500000 (with the same minimum weights as mentioned above). The number average molecular weight may be determined by size exclusion chromatography (SEC), gel permeation chromatography (GPC), matrix assisted laser desorption/ionizabon mass spectrometry (MALDI-MS) or, if the initiator carries a group which can be easily distinguished from the monomer(s), by NMR spectroscopy or other conventional methods.
The (co)polymers of the present invention typically have a low polydispersity. Preferably the polydispersity is from 1.1 to 2.2, more preferably from 1.1 to 1.9 and most preferably from 1.2 to 1.8.
Thus, the present invention also encompasses in the synthesis novel block, multi-block, star, gradient, random, hyperbranched and dendritic copolymers, as well as graft or copolymers.
The polymers prepared by the present invention are useful for following applications:
adhesives, detergents, dispersants, emulsifiers, surfactants, defoamers, adhesion promoters, corrosion inhibitors, viscosity improvers, lubricants, rheology modifiers, thickeners, crosslinkers, paper treatment, water treatment, electronic materials, paints, coatings, photography, ink materials, imaging materials, superabsorbants, cosmetics, hair products, preservatives, biocide materials or modifiers for asphalt, leather, textiles, ceramics and wood.
Because the present polymerizaton is a xe2x80x9clivingxe2x80x9d polymerization, it can be started and stopped practically at will. Furthermore, the polymer product retains the functional alkoxyamine group allowing a continuation of the polymerization in a living matter. Thus, in one embodiment of this invention, once the first monomer is consumed in the initial polymerizing step a second monomer can then be added to form a second block on the growing polymer chain in a second polymerization step. Therefore it is possible to carry out additional polymerizations with the same or different monomer(s) to prepare multi-block copolymers. Furthermore, since this is a radical polymerization, blocks can be prepared in essentially any order. One is not necessarily restricted to preparing block copolymers where the sequential polymerizing steps must flow from the least stabilized polymer intermediate to the most stabilized polymer intermediate, such as is the case in ionic polymerization. Thus it is possible to prepare a multi-block copolymer in which a polyacrylonitrile or a poly(meth)-acrylate block is prepared first, then a styrene or butadiene block is attached thereto, and so on.
Furthermore, there is no linking group required for joining the different blocks of the present block copolymer. One can simply add successive monomers to form successive blocks.
A plurality of specifically designed polymers and copolymers are accessible by the present invention, such as star and graft (co)polymers as described, inter alia, by C. J. Hawker in Angew. Chemie, 1995, 107, pages 1623-1627, dendrimers as described by K. Matyaszewski et al. in Macrmolecules 1996, Vol 29, No.12, pages 4167-4171, graft (co)polymers as described by C. J. Hawker et al. in Macromol. Chem. Phys. 198, 155-166(1997), random copolymers as described by C. J. Hawker in Macromolecules 1996, 29, 2686-2688, or diblock and triblock copolymers as described by N. A. Listigovers in Macromolecules 1996, 29, 8992-8993.
Yet another object of the present invention is a polymer or oligomer, having at least one initiator group xe2x80x94CR1R2R3 and at least one oxyamine group of formula (IIa) 
wherein n, R1, R2, R3, R10 R11 and R12 have the meanings and preferred meanings as defined above, obtainable by the process as defined above.
In another of its aspects, this invention relates to a compound of formula (I) 
wherein n is 0 or 1
R1, R2, R3 are each independently of one another hydrogen, halogen, NO2, cyano, xe2x80x94CONR5R6, xe2x80x94(R9)COOR4, xe2x80x94C(O)xe2x80x94R7, xe2x80x94OR8, xe2x80x94SR8, xe2x80x94NHR8, xe2x80x94N(R8)2, carbamoyl, di(C1-C18alkyl)carbamoyl, xe2x80x94C(xe2x95x90NR5)(NHR6);
unsubstituted C1-C18alkyl, C2-C18alkenyl, C2-C18alkynyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or
C1-C18alkyl, C2-C18alkenyl, C2-C18 alkynyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or
phenyl, naphthyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or R2 and R3, together with the linking carbon atom, form a C3-C12 cycloalkyl radical, a (C4-C12 cycloalkanon)-yl radical or a C3-C12cycloalkyl radical containing at least one O atom and/or a NR8 group; or if n is 1
R4 is hydrogen, C1-C18alkyl, phenyl, an alkali metal cation or a tetraalkylammonium cation;
R5 and R6 are hydrogen, C1-C18alkyl, C2-C18alkyl which is substituted by at least one hydroxy group or, taken together, form a C2-C12alkylene bridge or a C2-C12-alkylene bridge interrupted by at least one O or/and NR8 atom;
R7 is hydrogen, C1-C18alkyl or phenyl;
R8 is hydrogen, C1-C18alkyl or C2-C18alkyl which is substituted by at least one hydroxy group;
R9 is C1-C12alkylen or a direct bond;
R10 is C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom, C9-C11phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom, C9-C11phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or
phenyl, naphthyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or a polycyclic cycloaliphatic ring system or a polycyclic cycloaliphatic ring system with at least one di- or trivalent nitrogen atom;
if n is 1 one nitrogen or oxygen atom; or
C1-C18alkyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or phenyl, naphthyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or a polycyclic cycloaliphatic ring system or a polycyclic cycloaliphatic ring system with at least one di- or trivalent nitrogen atom; or
R10 and R11 together form a C2-C12alkylene bridge, a C3-C12alkylen-on bridge or a C2-C12alkylene bridge which is interrupted by at least one O or N atom, which bridges are unsubstituted or substituted with C1-C18alkyl, hydroxy(C1-C4)alkyl, phenyl, C7-C9phenylalkyl, NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino, or
R12 is hydrogen, xe2x80x94(R9)COOR4, cyano, xe2x80x94OR8, xe2x80x94SR8, xe2x80x94NHRa, xe2x80x94N(R8)2, xe2x80x94NHxe2x80x94C(O)xe2x80x94R8, unsubstituted C1-C18alkyl, C2-C18alkenyl, C2-C18alkynyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or
C1-C18alkyl, C2-C18alkenyl, C2-C18 alkynyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or
phenyl, naphthyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino, di(C1-C4alkyl)amino; or R11 and R12 together with the linking carbon atom, form a C3-C12 cycloalkyl radical;
with the proviso that
if n is 0 R10 is different from the group xe2x80x94CR1R2R3, and if R1 is CN and R2 and R3 are methyl, R10 is not phenyl, phenyl substituted by methyl, 2,4,6-trimethyl, chlor, fluor, (3-methyl,4-fluor), (3-fluor, 4-methyl), (4-fluor, 2-methyl), (4-fluor, 2-methoxy), (2-fluor, 3,5-methyl), 2,5-di-tert.butyl, nitro, 3,5-dinitro or 2 (xe2x80x94Oxe2x80x94C(CH3)2CN) 4-nitro; and
if n is 1, R12 is hydrogen, R10 phenyl or benzyl and R11 yl,
R1, R2 and R3 are not a group xe2x80x94C(CH3)2CN, xe2x80x94C(CH3)2COOCH3, benzyl, methylbenzyl, dimethylbenzyl, 
and the compound according to formula I is not 
Preferred compounds are those wherein n is 0 or 1;
R1, R2, R3 are each independently of one another NO2, cyano, xe2x80x94C(O)xe2x80x94R7, xe2x80x94OR8, unsubstituted C1-C12alkyl or phenyl, which is unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino;
or R2 and R3, together with the linking carbon atom, form a C5-C7 cycloalkyl radical;
R7 is, C1-C8alkyl or phenyl;
R8 is C1-C8alkyl or C2-C8alkyl which is substituted by at least one hydroxy group and R10 is C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom, phenyl or C9-C11phenylalkyl;
if n is 1
R11 is C1-C18alkyl, C7-C9phenylalkyl or C3-C12cycloalkyl or R10 and R11 together form a C2-C6alkylene bridge which is unsubstituted or substituted with C1-C4alkyl;
R12 is, unsubstituted C1-C4alkyl or phenyl.
Particularly preferred are compounds wherein n is 0;
R1 is cyano;
R2 and R3 are each independently of one another unsubstituted C1-C12alkyl or phenyl; or R2 and R3, together with the linking carbon atom, form a C5-C7 cycloalkyl radical; R10 is C4-C12alkyl bound via a tertiary C-atom to the nitrogen atom or C9-C11iphenylalkyl.
Another particularly preferred group of compounds are those wherein n is 1;
R1 is cyano;
R2 and R3 are each independently of one another unsubstituted C1-C12alkyl or phenyl; or R2 and R3, together with the linking carbon atom, form a C5-C7 cycloalkyl radical; R10 is C4-C12alkyl bound via a tertiary C-atom to the nitrogen atom, C9-C11phenylalkyl or phenyl; or
R10 and R11 together form a C2-C6alkylene bridge which is unsubstituted or substituted with C1-C4alkyl; and
R12 is C1-C4alkyl.
Further meanings and preferrences for the different substitutents R1 to R12 are mentioned before.
The invention is also directed to a compound of formula (IV) 
wherein n is 0 or 1
R1, R2, R3 are each independently of one another hydrogen, halogen, NO2, cyano, xe2x80x94CONR5R6, xe2x80x94(R9)COOR4, xe2x80x94C(O)xe2x80x94R7, xe2x80x94OR8, xe2x80x94SR8, xe2x80x94NHR8, xe2x80x94N(R8)2, carbamoyl, di(C1-C18alkyl)carbamoyl, xe2x80x94C(xe2x95x90NR5)(NHR6);
unsubstituted C1-C18alkyl, C2-C18alkenyl, C2-C18alkynyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or
C1-C18alkyl, C2-C18alkenyl, C2-C18 alkynyl, C7-C9phenylalkyl, C3-C12cyctoalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or
phenyl, naphthyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or R2 and R3, together with the linking carbon atom, form a C3-C12 cycloalkyl radical, a (C4-C12 cycloalkanon)-yl radical or a C3-C12cycloalkyl radical containing at least one O atom and/or a NR8 group; or if n is 1
R4is hydrogen, C1-C18alkyl, phenyl, an alkali metal cation or a tetraalkylammonium cation;
R5 and R6 are hydrogen, C1-C18alkyl, C2-C18alkyl which is substituted by at least one hydroxy group or, taken together, form a C2-C12alkylene bridge or a C2-C12-alkylene bridge interrupted by at least one O or/and NR8 atom;
R7 is hydrogen, C1-C18alkyl or phenyl;
R8 is hydrogen, C1-C18alkyl or C2-C18alkyl which is substituted by at least one hydroxy group;
R9 is C1-C12alkylen or a direct bond;
R10 is C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom, C9-C11phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or C4-C18alkyl bound via a tertiary C-atom to the nitrogen atom, C9-C11phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or
phenyl, naphthyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or a polycyclic cycloaliphatic ring system or a polycyclic cycloaliphatic ring system with at least one di- or trivalent nitrogen atom;
if n is 1
R11 is C1-C18alkyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or
C1-C18alkyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or
phenyl, naphthyl,, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino or di(C1-C4alkyl)amino; or a polycyclic cycloaliphatic ring system or a polycyclic cycloaliphatic ring system with at least one di- or trivalent nitrogen atom; or
R10 and R11 together form a C2-C12alkylene bridge, a C3-C12alkylen-on bridge or a C2-C12alkylene bridge which is interrupted by at least one O or N atom, which bridges are unsubstituted or substituted with C1-C18alkyl, hydroxy(C1-C4)alkyl, phenyl, C7-C9phenylalkyl, NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino;
R12 is hydrogen, xe2x80x94(R9)COOR4, cyano, xe2x80x94OR8, xe2x80x94SR8, xe2x80x94NHR8, xe2x80x94N(R8)2, xe2x80x94NHxe2x80x94C(O)xe2x80x94R8, unsubstituted C1-C18alkyl, C2-C18alkenyl, C2-C18alkynyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom; or
C1-C18alkyl, C2-C18alkenyl, C2-C18 alkynyl, C7-C9phenylalkyl, C3-C12cycloalkyl or C3-C12cycloalkyl containing at least one nitrogen or oxygen atom, which are substituted by NO2, halogen, amino, hydroxy, cyano, carboxy, C1-C4alkoxy, C1-C4alkylthio, C1-C4alkylamino or di(C1-C4alkyl)amino; or
phenyl, naphthyl, which are unsubstituted or substituted by C1-C4alkyl, C1-C4alkoxy, C1-C4alkylthio, halogen, cyano, hydroxy, carboxy, C1-C4alkylamino,
di(C1-C4alkyl)amino; or
R11 and R12 together with the linking carbon atom, form a C3-C12cycloalkyl radical;
with the proviso that
if n is 0 R10 is different from the group xe2x80x94CR1R2R3, and if R1 is CN and R2 and R3 are methyl, R10 is not phenyl, phenyl substituted by methyl, 2,4,6-trimethyl, chlor, fluor, (3-methyl,4-fluor), (3-fluor, 4-methyl), (4-fluor, 2-methyl), (4-fluor, 2-methoxy), (2-fluor, 3,5-methyl), 2,5-di-tert.butyl, nitro, 3,5-dinitro or 2 (xe2x80x94Oxe2x80x94C(CH3)2CN) 4-nitro; and
if n is 1, R12 is hydrogen, R10 phenyl or benzyl and R11 phenyl, R1, R2 and R3 are not a group xe2x80x94C(CH3)2CN, xe2x80x94C(CH3)2COOCH3, benzyl, methylbenzyl, dimethylbenzyl, 
and the compound according to formula IV is not 
Meanings and preferences for the different substitutents R1 to R12 are already mentioned.
A further object of the present invention is a process for preparing a compound of formula (I) 
by generating a free radical xe2x80xa2CR1R2R3 (V) from a compound capable of eliminating a neutral molecule, or undergoing C-C bond-scission upon thermal or photochemical treatment, or by hydrogen abstraction from a compound R1R2R3Cxe2x80x94H in reaction with reactive radicals, and reacting the free radical xe2x80xa2CR1R2R3 (V) with a compound of formula R10NO or 
in a solvent which does not interfere with the radical reaction.
Examples for neutral molecules which can be eliminated are N2 or O2. Reactive radicals which are able to abstract hydrogen are for example alkoxy radicals.
Suitable solvents are aromatic, aliphatic or cycloaliphatic hydrocarbons, such as toluene, benzene xylene, octane or cyclohexane, ethers, such as dioxane, tetrahydrofurane or dibutylether, alcohols, glycols or esters and amides of carboxylic acids.
The free radical xe2x80xa2CR1R2R3 is preferably prepared by heating or irradiation of a compound of formula IIIa, IIIb or IIIc 
Preferably the radical xe2x80xa2CR1R2R3 is prepared by a thermal reaction at a temperature from 40xc2x0 to 150xc2x0 C., more preferrably from 60xc2x0 to 150xc2x0 C. and most preferrably from 70xc2x0 to 140xc2x0 C. R1, R2 and R3 have the meanings and preferred meanings defined above.
Nitrones of formula (VI) can be prepared according to known methods.
Examples of 5-membered nitrones are for example described by J. B. Bapat and D. St. C. Black in Aust. J. Chem. 21, 2483 (1968). Typical examples are mentioned below. 
Further nitrones are described by H. Gnichtel, K. E. Schuster in Chem. Ber. 111, 1171 (1978). 
A. G. Krainev, T. D. Williams, D. J. Bigelow describe in J. Magnet. Res., B 111, 272 (1996) the preparation of following nitrones. 
Examples of 6-membered nitrones are for example described by Shun-Ishi Murahashi et al. in J. Org. Chem. 55 1736 (1990). 
These nitrones may be reacted with the appropriate reactive radical xe2x80xa2CR1R2R3 to obtain compounds of formula (I).
Some reaction products between nitrones and reactive radicals have been reported and are listed below.
M. Iwamura, N. Inamoto: Bull. Chem. Soc. Japan 43,856 (1970): 
or D. A. Becker: J.Am. Chem. Soc. 118, 905 (1996). 
M. lwamura, N. lnamoto: Bull. Chem. Soc. Japan 43, 860 (1970) have reported the preparation of the following compound. 
None of these compounds have been used to polymerize ethylenically unsaturated monomers or oligomers.
The production of C-centered radicals is described, inter alia, in Houben Weyl, Methoden der Organischen Chemie, Vol. E 19a, pages 60-147. These methods can be applied in general analogy.
The reaction of reacting radicals with nitroso compounds is known per se and described by B. A. Gingras et al. in J. Chem. Soc. page 1920,1954.
Most preferably, the free radical source is 2,2xe2x80x2-azobisisobutyronitrile, 2,2xe2x80x2-azobis(2-methylbutyronitrile), 2,2xe2x80x2-azobis(2,4-dimethylvaleronitrile), 2,2xe2x80x2-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1xe2x80x2-azobis(1-cyclohexanecarbonitrile), 2,2xe2x80x2-azobis(isobutyramide) dihydrate, 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, dimethyl-2,2xe2x80x2-azobisisobutyrate, 2-(carbamoylazo)isobutyronitrile, 2,2xe2x80x2-azobis(2,4,4-trimethylpentane), 2,2xe2x80x2-azobis(2-methylpropane), 2,2xe2x80x2-azobis(N,Nxe2x80x2-dimethyleneisobutyramidine), free base or hydrochloride, 2,2xe2x80x2-azobis(2-amidinopropane), free base or hydrochloride, 2,2xe2x80x2-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)ethyl]propionamide} or 2,2xe2x80x2-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide.
These compounds are commercially available.
If more than one radical source is used, a mixture of substitution patterns is obtainable. This invention also relates to the use of an initiator compound of formula (I) for polymerizing ethylenically unsaturated monomers.
The alkoxyamines of formula (I) may be prepared and isolated as described above. However, it is also possible to produce the compounds of formula (I) in situ during polymerization by adding a compound of formula IV, which has been isolated as intermediate in the process described before, to the polymerizable monomers and by adding, also in situ, the corresponding radical initiator.
Consequently a further aspect of the invention is a polymerizable composition, comprising
a) at least one ethylenically unsaturated monomer or oligomer;
b) a compound of formula (IV) and
c) a radical initiator as described above capable of generating a free radical of formula (V) 
wherein n, R1, R2, R3, R10, R11 and R12 are as defined above including their preferences.
Still another aspect of the invention is a process for preparing an oligomer, a cooligomer, a polymer or a copolymer (block or random) by free radical polymerization of at least one ethylenically unsaturated monomer/oligomer, which comprises subjecting a composition as described above to heat or actinic radiation.
A further aspect of the present invention is the use of a compound of formula I for polymerizing ethylenically unsaturated monomers.
Suitable initiators are those listed above including their preferrences.